The magnetic properties of loop antennas make such antennas useful for radio receivers to be used on or near the human body (e.g. pagers). The bandwidth of loop antennas offers selectivity to received-signal frequencies, but has the drawback of limited received-frequency range without tuning or adjustment. Varactors and saturated core inductors are commonly used electronically-tuned elements; both exhibit nonlinear behavior. The drawback of using those elements is degraded receiver distortion rejection. The use of loop antennas has thus been confined to narrow-frequency range applications or for use in conjunction with mechanical tuning.